rearranging a string.new

[drock]

In my situation I have a string like so:

my $string = '20050516';

and I want to rearrange it to look like: 05162005, so I tried:

my $newstring = substr($string,0,8).substr($string,0,4).substr($string
+,8,0);

But my problem is: it's leaving 2005 in the beginning of the string to look like 200505162005 when all I need is 05162005 thx derek

[ikegami]

Your arguments were completely wrong. Maybe you should reread the documentation for substr. Corrected:

my $newstring = substr($string, 4, 2)   # Month (was at 4 len 2)
              . substr($string, 6, 2)   # Day   (was at 6 len 2)
              . substr($string, 0, 4);  # Year  (was at 0 len 4)

which can be simplified to

my $newstring = substr($string, 4, 4)   # M+D  (was at 4 len 4)
              . substr($string, 0, 4);  # Year (was at 0 len 4)

[VSarkiss]

The other responses in this thread are addressing your problem directly, but I wanted to point out an alternative.

In general, fixed-length string decomposition is easiest with unpack (and if necessary, its companion pack). Your particular example can be accomplished with:

my $newstring = join '' => reverse unpack('a4 a4', $string);

Golf anyone? :-)

[davidrw]

Can also use a regex or substitution...

my $string = '20050516';

my $newstring;
$newstring = $2 . $1 if $string =~ /(\d{4})(\d{4})/;
warn $newstring;

(my $newstring = $string) =~ s/(\d{4})(\d{4})/$2$1/;
warn $newstring;

Could also use a more robust regex if desired (trivial example is /(200[012345])(\d{4})/) and depending on context.

[Corion]

It's not "leaving the 2005 in front". Check your code, for example by running the below code:

my $string = '20050516';
my $newstring = substr($string,0,8). "!" . substr($string,0,4) . "!" .
+ substr($string,8,0);
print $newstring;

If you look at the output of this snippet, you will see where your errors lie.

[ptum]

You may want something more like:

my $newstring = substr($string,4,2) . substr($string,6,2) . substr($st
+ring,0,4);